Many MindedScientists say an overshoot of 1.5C would lock in ice loss for centuries
A report from 80 scientists, convened by the International Cryosphere Climate Initiative and the UN Environment Programme, examines what happens to the world's ice if warming overshoots the Paris Agreement's 1.5C target. Its answer is that much of the damage cannot be undone. It was released as the 31st Cop climate conference convenes in Turkey.
The planet has warmed about 1.3C since pre-industrial times, and current policies point to a peak near 3C. The report says that would thaw nearly all near-surface permafrost and make severe, possibly abrupt, ocean circulation disruption likely. Greenland and Antarctica are already melting about six times faster than in the 1990s, and would keep losing ice even if a brief overshoot returned to 1.5C. The authors put a safe long-term limit for polar ice sheets nearer 1.0C, possibly lower.
Glacier figures show the stakes for water. At 2.8C, glacier mass would fall below 10% in the Rockies, Alps, Iceland and Scandinavia, against 20-35% remaining at 1.5C. In the Hindu Kush Himalayas, 41% of ice would remain versus 83% at 1.5C. Those glaciers supply water to nearly a quarter of humanity. Lead author James Kirkham pointed to a deadly avalanche on the Nepal-China border this year and to Switzerland's loss of 20% of its glacier ice in five years.
For abundance, this is a setback: water security, coastal housing and food production all get costlier and less certain when the ice base is lost for centuries. Watch what Cop31 does with the gap, since a UNEP report last month said emissions must fall 18% by 2030 and 45% by 2035 for a good chance of holding to 1.7C. A caveat: the report's goal of returning below 1C, ideally by 2150, depends on large-scale carbon removal that the source does not quantify. Sea ice recovery is described as slower than once thought, but that rests on the latest research and is not a settled figure.
Source: Guardian